ZnTe 단결정 박막의 결정구조와 광학적 특성 연구

ZnTe epilayers were grown on GaAs (100) substrates by using the hot-wall epitaxy method. X-ray diffraction (XRD) was used to study the crystallinity and the crystal orientation of the epilayer. The surface morphology of the epilayer was observed by using a field-emission scanning electron microscope (FESEM). In order to investigate the binding states and their chemical compositions, we characterized the ZnTe epilayers by using X-ray photoelectron spectroscopy (XPS). Their optical properties were investigated in the photon energy range between 1.5 and 8.7 eV at room temperature by using spectroscopic ellipsometry (SE). The obtained data were analyzed for the critical points, such as the E_0, E_0+△_0, E_1, E_1+△_1, Estructures, of the pseudodielectric function spectra <ε(E)> = <ε_1 (E)> +i<ε_2(E)>. Also, the pseudodielectric-function-related optical constants of ZnTe, such as the refractive index n(E) and the extinction coefficient k(E), were analyzed. Numerical calculations of second derivative spectra of the pseudodielectric functions <ε(E)> of our ZnTe epilayer were carried out for a further analysis of the critical points. We observed the E_1, E_1+ △_1 peaks at energies above 6.0 eV through the SE analysis.